In the game of golf, knowing the dynamics of the club head and shaft during the swing is useful for equipment design, practice and instruction. Those characteristics include the club head speed, club head orientation, contact point of the ball on the club face and swing path. As is apparent from this list, the angle, position and speed of the club head as it impacts the ball is critical to the ultimate golf ball trajectory.
To address this problem, previous systems have used multiple cameras and reflective spheres such as the system shown in FIG. 8. Relatively large round reflective spheres 805 are attached to the head 810 and shaft 815 of the club. The markers protrude from the head and shaft and can be easily damaged or have adverse effect on the golfers swing. The spheres although light are not insignificant and can affect the weight and aerodynamics of the swing. The spheres also prevent the club from being inserted into a golf bag. Initially these spheres have no known relationship to the club face. A complicated procedure using a calibration fixture is required to determine the relationship between the arbitrary spheres and the club face.
What is needed is a system that is easy to install, does not require calibration, and does not adversely affect or influence a golfer's swing.